Search Results (1,069)

Background/Objectives: Patients in long-term care hospitals (LTCHs) are at increased risk of harboring antimicrobial-resistant organisms due to frequent healthcare exposure and multiple comorbidities. This retrospective observational study aimed to compare the antimicrobial susceptibility of bacterial isolates from LTCH-onset infections (LTCHIs) with those from community-acquired infections (CAIs) in elderly patients. Methods: This study was conducted at a 700-bed urban tertiary university hospital and included patients aged ≥65 years with positive cultures for bacteremia, lower respiratory tract infections (LRTIs), or urinary tract infections (UTIs) within 48 h of admission. Medical records, including antimicrobial susceptibility test results, were reviewed for a total of 1780 patients and their isolates. Antimicrobial susceptibility patterns were compared between LTCHI and CAI patients. Results: Patients with LTCHI exhibited significantly higher antimicrobial non-susceptibility than those with CAIs across multiple pathogens and antimicrobial classes (p < 0.05). In bacteremia, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae from LTCHI cases showed increased non-susceptibility to β-lactams and fluoroquinolones. In LRTIs, Pseudomonas aeruginosa and Acinetobacter baumannii demonstrated high non-susceptibility to carbapenems (52.9% and 90%, respectively) and aminoglycosides. In UTIs, LTCHI isolates exhibited broader resistance among Enterobacterales and P. aeruginosa. Notably, the proportion of multidrug-resistant organisms, including carbapenem-resistant Enterobacterales (15.4–50.0%) and carbapenem-resistant Acinetobacter baumannii (90.5%), was substantially higher in the LTCHI group across all infection sites. Conclusions: Elderly patients with LTCHI are more likely to harbor antimicrobial-resistant pathogens than those with CAIs. Careful consideration of LTCHI origin is therefore essential for empirical antibiotic selection and for strategies aimed at limiting further resistance. Full article

Caloric restriction (CR) is known to activate a broad spectrum of cytoprotective signaling pathways and enhance tissue tolerance to various stressors, including those associated with the cytotoxic effects of pharmaceutical agents. Nephrotoxic drugs, such as aminoglycoside antibiotics, remain a major clinical concern due to their frequent use and potential to cause acute kidney injury (AKI), for which effective preventive strategies are still limited. In this study, we investigated whether CR applied for 5 weeks (4-week pretreatment + 1-week concurrent with AKI induction) can alleviate AKI triggered by the antibiotic gentamicin, with a focus on evaluating changes in antioxidant-related parameters and autophagy-associated signaling during CR-mediated nephroprotection. CR’s nephroprotective effects were evaluated using diagnostic assays, Western blotting, and histological analysis. Additionally, oxidative stress markers and mitochondrial integrity were assessed to analyze the impact of CR on antioxidant-related pathways. CR significantly improved renal function and structure, with reduced kidney injury markers (KIM-1, NGAL) and alleviated histological damage. Critically, CR mitigated oxidative stress, evidenced by decreased thiobarbituric acid reactive substances (TBARS) and protein carbonylation, as well as increased levels of the reduced form of glutathione and activity of glutathione peroxidase (GPx). A lowered Bcl-X_L/X_S ratio was consistent with reduced apoptotic signaling, while reduced leukocyte infiltration reflected attenuated renal inflammation. Additionally, a reduction in mitochondrial DNA (mtDNA) lesions suggested that CR was associated with modulation of mitochondrial and metabolism-related pathways, with concurrent improvements in mitochondrial stability. Our findings demonstrate that CR attenuated gentamicin-induced AKI and was associated with changes in antioxidant-related parameters, reduced mtDNA damage, a decrease in inflammatory cell infiltration, and modulation of autophagy-related signaling. Full article

Background/objectives: Infections caused by multidrug-resistant (MDR) bacteria are becoming increasingly difficult to treat with recommended antimicrobials. Considering the critical and growing challenge of antimicrobial resistance (AMR), this study aims to evaluate the antimicrobial susceptibility patterns of Escherichia coli clinical isolates from dogs in Grenada. This research project consists of two distinct studies: a retrospective analysis of AMR in canine E. coli isolates collected between 2010 and 2020, and a cross-sectional study characterizing the genotypic AMR profiles of E. coli isolates obtained between April and June 2023. Methods: A retrospective analysis of antibacterial sensitivity test (ABST) reports from canine clinical samples submitted to the Small Animal Clinic at St. George’s University (SGU), St. George’s, Grenada, between 2010 and 2020 revealed a notable prevalence of AMR among canine E. coli isolates. To further investigate the underlying mechanisms of this resistance, the study analyzed canine E. coli isolates that exhibited phenotypic resistance in ABST assays. These isolates were subsequently screened for AMR-associated genes using polymerase chain reaction (PCR) and next-generation sequencing (NGS). Results: The retrospective study identified 153 canine clinical isolates positive for E. coli. The antimicrobial drugs, imipenem, cefotaxime and ciprofloxacin were found to be highly effective against these isolates. However, a gradual increase in AMR was observed for amoxicillin–clavulanic acid (34.88%), ampicillin–sulbactam (17.31%), cephalexin (43.08%), cefpodoxime (22.31%), cephalothin (68.42%), and doxycycline (37.04%). In the prospective study, PCR analysis of resistant canine E. coli isolates detected the tetA (577 bp) and blaTEM (686 bp) genes. These AMR determinants were further confirmed through analysis of NGS reads and assembled contigs. Additionally, NGS-based predictions identified genes associated with resistance to aminoglycosides and potentiated sulfonamides. Conclusions: This study demonstrates that E. coli from dogs in Grenada exhibits resistance to tetracycline and several β-lactam antimicrobials. These findings underscore the need for rational antimicrobial stewardship and continuous AMR surveillance in small animal practice within the region. Full article

Background/Objectives: Multidrug resistant (MDR) Salmonella represents a major global public health challenge within the One Health interface. This study aimed to characterize the genomic epidemiology of Salmonella isolates from Colombia and resolve the genetic architecture of novel MDR plasmids identified in foodborne strains. Methods: A total of 90 Salmonella isolates collected between 2002 and 2009 from various food sources and food-producing animals in Colombia were analyzed using whole-genome sequencing (WGS). Bioinformatics tools were employed for serotype prediction, multi-locus sequence typing (MLST), and resistome/virulome profiling. Long-read sequencing was utilized to close the complete sequences of representative MDR plasmids. Results: 45.6% of isolates exhibited antimicrobial resistance, with seven being classified as MDR. The major serotypes identified were Uganda (n = 20), Newport (n = 10), and Braenderup (n = 10). We characterized a novel 229,037 bp IncHI1 plasmid (pCFS0255-1) harboring a copper homeostasis and silver resistance island (CHASRI) integrated with tetracycline and macrolide resistance clusters. Additionally, a 99,288 bp IncI1 plasmid (pCFS0255-2) carrying a unique aminoglycoside resistance module was resolved. Conclusions: Our findings highlight the persistence of specific Salmonella lineages in the Colombian food chain and the role of hybrid plasmids in the co-selection of metal and antibiotic resistance. The study underscores the necessity of implementing WGS-based surveillance to track emerging MDR threats. Full article

Background/Objectives: Children with congenital urogenital anomalies (CUA) face increased risk of urinary tract infections (UTIs) and may harbor resistant organisms due to recurrent infections and antibiotic exposure. This study characterized the distribution of uropathogens and antimicrobial resistance patterns at a tertiary center in Saudi Arabia. Methods: This retrospective cohort study included pediatric patients (<18 years) with documented congenital urogenital anomalies and positive urine cultures at King Khalid University Hospital, Riyadh (2015–2025). Susceptibility interpretations (S/I/R) were extracted from the hospital laboratory information system; multidrug resistance (MDR) was defined using organism-specific Magiorakos criteria. Results: A total of 168 patients (72.0% male; mean age 4.1 ± 4.5 years) contributed 411 UTI episodes. Among 403 mono-organism episodes (after excluding eight polymicrobial cultures), Escherichia coli predominated (150/403, 37.2%), followed by Klebsiella pneumoniae (96/403, 23.8%) and Pseudomonas aeruginosa (33/403, 8.2%). High resistance was observed for ampicillin (83.6%), trimethoprim-sulfamethoxazole (54.2%), and cephalosporins (cefazolin 62.8%, cefotaxime 35.6%). Carbapenems (2.9%) and aminoglycosides (9.2%) retained >90% susceptibility. Overall MDR was 35.5%, highest among Klebsiella oxytoca (57.1%) and Escherichia coli (47.6%). Recurrent infections showed numerically higher unadjusted resistance than single episodes. Conclusions: Pediatric patients with congenital urogenital anomalies showed high first-line antibiotic resistance. Carbapenems and aminoglycosides retained predominantly susceptible in vitro profiles in this cohort and may inform empiric considerations alongside ongoing local susceptibility surveillance for this high-risk population. Full article

This study used three complementary datasets to investigate the relationship between human Campylobacter infections in Estonia and potential sources. A targeted dataset of 15 C. jejuni genomes with overlapping sequence types from human cases and broiler chicken meat was analysed using genotyping and in silico antimicrobial resistance profiling, alongside 20 human isolates for source attribution. Additionally, 12,111 isolates were analysed to provide population-level context. The core genome multilocus sequence typing showed a high similarity (less than three allelic differences) between the human and broiler isolates of ST122, ST464, and ST7355, indicating poultry as a likely source, whereas ST9882 was more divergent (13–18 allelic differences). The resistance profiles were consistent within ST122, ST464, and ST7355, and all were resistant to ciprofloxacin, nalidixic acid, ampicillin, and tetracycline, while ST9882 additionally exhibited aminoglycoside (streptomycin) resistance. The source attribution linked 77.8% of the human cases to chicken and 22.2% to cattle. A novel genotype, ST11001, was identified in humans and attributed to cattle source, while C. coli isolates were linked to birds and sheep. Poultry dominated the larger dataset (87.3%). Gastroenteritis was the predominant clinical presentation (98.5%), whereas ST22 and ST122 were associated with Guillain–Barré syndrome. These findings support poultry as a major reservoir of human Campylobacter infections and highlight the need for coordinated cross-border surveillance. Full article

During the COVID-19 pandemic carbapenem-resistant Acinetobacter baumannii (CRAB) was found to be the major pathogen associated with ventilator-associated pneumonia in mechanically ventilated patients. This prompted us to analyze the post-pandemic mechanisms of carbapenem resistance, antibiotic resistance trends, and molecular epidemiology of CRAB in Croatia. In total, 94 CRAB isolates from two hospital centers, including outpatient settings, were investigated. Antimicrobial susceptibility testing was performed by broth microdilution. PCR was used to detect genes encoding carbapenemases of group A, B and D and extended-spectrum β-lactamases (ESBL). Randomly selected isolates were subjected to whole resistome analysis by Inter-array CarbaResist Kit and whole-genome sequencing (WGS). Phylogenetic tree and sequence types (STs) were retrieved from WGS. Plasmid incompatibility groups were determined by PCR-based replicon typing (PBRT). All isolates were extensively drug resistant (XDR), showing resistance to ceftazidime, cefepime, piperacillin–tazobactam, imipenem, meropenem, gentamicin, amikacin and ciprofloxacin, and 13% (n = 12) were also resistant to colistin. The Hodge and CIM test exhibited poor sensitivity with only 32 and 30% of isolates being identified as carbapenemase producers, respectively. PCR identified bla_OXA-23 as the dominant carbapenemase gene in both hospitals, found in 71% of the isolates (67/94). In an outpatient setting, bla_OXA-24/40 was dominant. bla_OXA-23 and bla_OXA-72 were the only allelic variants. The Inter-array CarbaResist Kit and whole-genome sequencing (WGS) identified a variety of aminoglycoside (armA, ant(3″)-IIa, aph(3″)-Ib, aph(6)-Id) and sulphonamide resistance (sul1 and sul2) genes. The representative bla_OXA-23-positive isolates belonged to ST2, while bla_OXA-72-positive isolates were allocated to ST492. These data show that there are different populations of XDR A. baumannii between hospital and outpatients. Full article

Aminoglycoside resistance is commonly mediated by enzymatic modification, target alteration, or efflux mechanisms; however, acquired resistance has not been characterized in radiation-resistant Deinococcus species. Here, we investigated the occurrence and genomic context of acquired aminoglycoside resistance genes in all publicly available Deinococcus radiodurans genomes. A total of 19 genomes were screened using ResFinder and CARD, followed by comparative genomic analyses. The aadA1 gene was identified in two genomes, being located on the plasmid pSP1 in strain R1 dM1, a known shuttle vector used for genetic manipulation. In contrast, aadA1 was found on a chromosomal contig in strain DRR11, suggesting a possible assembly artifact. Additionally, the aph(3′)-Ia gene was detected in three genomes within a conserved chromosomal region that lacks this gene in reference strains. Sequence similarity analyses indicated that aph(3′)-Ia is associated with laboratory vectors, being consistent with a potential non-natural origin. Considering the high recombination capacity and genomic plasticity of D. radiodurans, these findings suggest that the detected aminoglycoside resistance genes may be derived from laboratory constructs, potentially combined with assembly inconsistencies or chromosomal integration events. Therefore, this study highlights the importance of integrating genomic context with molecular and evolutionary plausibility to avoid misinterpretation of antimicrobial resistance in extremophiles and model organisms, and underscores the importance of complementary raw-read analyses to distinguish natural acquisition from technical or laboratory-derived origins. Full article

Background/Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKp) remains a critical driver of antimicrobial resistance (AMR) in hospital settings worldwide. Methods: This study examined trends in CRKp bloodstream infections over a seven-year period (2019–2025) in a tertiary care hospital in Greece, with particular attention given to resistance patterns and patient outcomes, including the impact of the COVID-19 pandemic. Results: A total of 671 non-duplicate CRKp isolates were analyzed and classified into three groups: KPC producers (67.4%), dual carbapenemase producers (dual CP) (17.4%), and single metallo-β-lactamase (MBL) producers (15.2%). Overall incidence showed a slight but non-significant increase over time. KPC-producing strains rose significantly until 2022 (p < 0.001), followed by a marked decline (p < 0.001). In contrast, dual CPs—mainly KPC combined with VIM or NDM—and single-MBL producers, particularly NDM, increased steadily, indicating a notable epidemiological shift. Resistance to aminoglycosides and tigecycline increased around 2021, followed by partial declines, whereas colistin resistance demonstrated a continuous upward trend throughout the study period. Despite phenotypic differences, overall mortality remained high, with no statistically significant differences between groups (p = 0.37), likely reflecting either the severity of patients’ clinical condition or inadequate empirical antibiotic therapy. Conclusions: This study highlights a dynamic evolution in CRKp epidemiology with decreasing KPC dominance and increasing prevalence of MBL- and dual CP strains. This transition, which became evident during and after the COVID-19 pandemic, underscores ongoing epidemiological adaptation and the urgent need for improved antimicrobial stewardship, rapid diagnostics, and broader access to effective therapies. Full article

Bacteria associated with unhatched sea turtle eggs remain poorly characterized at the genomic level. This study provides genome-scale characterization of bacterial isolates recovered from unhatched green sea turtle (Chelonia mydas) eggs at Akyatan Beach—a critical nesting site in the Eastern Mediterranean. Sampling 30 nests during the nesting season, we isolated bacteria from infected eggshells and dead embryos. Following Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry(MALDI-TOF MS) identification and 16S rRNA validation, we performed whole-genome sequencing (WGS) on Citrobacter farmeri and Enterobacter cloacae, two opportunistic pathogens of significant clinical and ecological concern. High-quality draft genomes revealed remarkable metabolic versatility, particularly within carbon and nitrogen pathways. Most notably, we identified extensive resistomes including resistance to $\beta$-lactams, fluoroquinolones, and aminoglycosides, alongside virulence factors for adhesion and iron acquisition. ANI analysis confirmed high genomic similarity to clinical reference strains, comparative genomic analysis revealed a substantial accessory gene pool, suggesting potential genomic flexibility between the two isolates. These findings provide the first genome-scale insight into these pathogens in C. mydas nests, and highlighting their genomic potential for opportunistic pathogenicity. Our results advocate for integrating genomic microbial surveillance into nesting beach management through a ‘One Health’ lens. Full article

Enterococcus lactis is increasingly recognized as an emerging mastitis pathogen, yet the functional basis of its virulence and associated health risks remain poorly defined. This study presents an integrated genomic and phenotypic characterization of E. lactis strain EL-A150 isolated from bovine subclinical mastitis. Whole-genome sequencing revealed a 2.49 Mb circular chromosome encoding multiple genes associated with adhesion (acm, bepA, fms, sagA), biofilm formation (empB, empC) and antimicrobial resistance, including determinants related to aminoglycosides and macrolides. Phenotypic assays demonstrated rapid growth, strong biofilm-forming capacity and high adhesion to bovine mammary epithelial cells, while internalization remained low and intracellular persistence was transient. Comparative genomic analyses confirmed the taxonomic placement of the strain within the E. lactis clade (ANI up to 99.5% against reference genomes) and revealed a limited resistome composed of chromosomally encoded genes, with no detectable plasmids or major mobile genetic elements. Collectively, these findings demonstrate that E. lactis EL-A150 possesses a coordinated set of traits conducive to intramammary colonization, supporting its classification as an opportunistic pathogen. The convergence of virulence potential and clinically relevant antimicrobial resistance within a single isolate underscores a One Health concern and highlights the need for surveillance frameworks that integrate functional validation with genomic risk assessment. Full article

Background: Staphylococcus pseudintermedius is a major opportunistic pathogen of dogs and the primary cause of canine pyoderma and other infections. The global emergence of methicillin-resistant S. pseudintermedius (MRSP) represents a significant challenge in veterinary medicine due to its frequent multidrug-resistant phenotype and limited therapeutic options. Methods: We describe the phenotypic and genomic characterization of an MRSP isolate recovered from a vaginal swab of an 11-year-old dog diagnosed with vulvovaginitis in southern Italy. Antimicrobial susceptibility testing was performed using broth microdilution according to CLSI VET01S guidelines. Whole-genome sequencing was conducted to determine sequence type and antimicrobial resistance determinants. Results: The isolate was identified as S. pseudintermedius by MALDI-TOF MS and confirmed by genomic analysis. Multilocus sequence typing assigned the strain to sequence type ST2333. Phenotypically, the isolate exhibited multidrug resistance, including resistance to β-lactams, macrolides, lincosamides, tetracyclines, aminoglycosides, fluoroquinolones, and trimethoprim–sulfamethoxazole, while remaining susceptible to amikacin, rifampicin, florfenicol, and vancomycin. Whole-genome sequencing confirmed the presence of mecA and additional resistance determinants consistent with the observed phenotype. Conclusions: This report suggests the possible occurrence of an MDR MRSP ST2333 lineage in southern Italy and highlights the importance of combined phenotypic and genomic surveillance to support antimicrobial stewardship in veterinary medicine within a One Health framework. Full article

Background/Objectives: Acinetobacter baumannii is a critical opportunistic pathogen causing severe healthcare-associated infections, particularly in intensive care units. The global dissemination of carbapenem-resistant A. baumannii (CRAB) and its environmental persistence necessitate continuous genomic surveillance to monitor high-risk clones. Methods: We conducted whole-genome sequencing (WGS), core genome multi-locus sequence typing (cgMLST), and phylogenomic analyses on 26 CRAB isolates collected at the National Institute for Infectious Diseases (INMI) “Lazzaro Spallanzani” IRCCS (September 2023–September 2024). Antimicrobial resistance determinants, virulence-related genes, and capsular (KL) and lipooligosaccharide outer core (OCL) loci were characterized by interrogation of comprehensive bioinformatic pipelines. Results: All CRAB isolates displayed an extensively drug-resistant (XDR) phenotype, with a shared resistance pattern to carbapenems, aminoglycosides, fluoroquinolones, fosfomycin, and sulfonamides, while being susceptible only to colistin and cefiderocol. The carbapenemase gene bla_OXA-23 was detected in all CRAB isolates, together with clone-specific bla_OXA-51-like variants. For all isolates, the resistome profile fully matched the observed resistance phenotype. All isolates belonged to the International Clonal Lineage II (ICL II), Pasteur Sequence Type (ST) 2, and Oxford ST369, ST208, and ST455. Integration of cgMLST data with phylogenomic analyses and genome-based classification of KL and OCL loci revealed five distinct clusters, each one including nearly identical isolates, indicating both intra-hospital dissemination and possible inter-hospital transmission. Virulome profiling revealed heterogeneous repertoires of virulence-associated genes, resulting in cluster-specific patterns, while patristic analysis identified phylogenetic clusters linking the study isolates to other Italian and other European lineages. Conclusions: This study underscores the complex genomic landscape of CRAB in our setting, driven by the circulation of different ICL II clonal types, and reinforces the urgency of integrated genomic surveillance and robust antimicrobial stewardship to mitigate the spread of high-risk XDR A. baumannii clones. Full article

Background: Acinetobacter baumannii is a non-fermenting Gram-negative bacillus responsible for severe nosocomial infections, particularly in intensive care units (ICUs). The increasing prevalence of multidrug-resistant (MDR) and carbapenem-resistant A. baumannii (CRAB) strains has become a significant challenge for infection control and antimicrobial therapy worldwide. Objectives: This study aimed to analyze the antimicrobial susceptibility patterns of clinical A. baumannii isolates recovered from a multi-profile hospital in years 2020–2024 in Lodz, Poland. Methods: Clinical isolates from various specimen types (blood, urine, wound swabs, biopsies, sputum, and bronchoalveolar lavage fluid) were obtained during routine microbiological diagnostics. Identification was performed using MALDI-TOF MS. Antimicrobial susceptibility testing (AST) was conducted using the automated VITEK^®2 system with EUCAST/CLSI interpretive criteria. Minimum inhibitory concentrations (MICs) for colistin were determined by broth microdilution. Carbapenemase production was assessed using the Carbapenem Inactivation Method (CIM) and immunochromatographic assays for OXA-23, OXA-40/58, and NDM detection. Results: A total of 244 A. baumannii isolates were recovered over the study period. Susceptibility to carbapenems (meropenem, imipenem) declined markedly, with resistance exceeding 90% by 2023–2024. Aminoglycosides exhibited variable activity, with gentamicin demonstrating the highest susceptibility rates (up to 88% in 2022). Resistance to ceftazidime and cefepime remained consistently high (>90% in 2023–2024). No fully susceptible isolates were identified for ciprofloxacin. Conclusions: The high prevalence of CRAB strains highlights the urgent need for effective infection control measures, optimized antimicrobial stewardship, and consideration of novel treatment options in the clinical setting. Full article

Background: Anti-MRSA agents are essential for treating severe infections, yet their use is constrained by distinct toxicity profiles. However, comparative real-world data remain scarce. Methods: This nationwide pharmacovigilance study used the Japanese Adverse Drug Event Report (JADER) database (2004–2025). Disproportionality analyses (proportional reporting ratio [PRR]) were performed at the Standardized MedDRA Query and Preferred Term levels, complemented by Weibull-based time-to-onset modeling, to characterize AE patterns associated with vancomycin (VCM), teicoplanin (TEIC), arbekacin (ABK), daptomycin (DAP), linezolid (LZD), and tedizolid (TZD). Results: Distinct agent-specific AE profiles were observed. VCM showed disproportionate reporting of acute renal failure (PRR 6.66) and severe cutaneous reactions. TEIC displayed fewer renal signals but relatively higher reporting of hematologic events (PRR 3.51). ABK demonstrated high disproportionality in acute and chronic renal failure, reflecting aminoglycoside nephrotoxicity. DAP showed a high reporting signal for eosinophilic pneumonia (PRR 23.30), interstitial lung disease, and creatine kinase elevation/rhabdomyolysis, with wear-out hazard patterns suggesting a possible time-dependent reporting tendency. LZD exhibited hematopoietic signals (PRR 6.13) and additional associations with hyponatremia, lactic acidosis, and optic neuropathy, consistent with marrow suppression and mitochondrial toxicity. Weibull analysis indicated cumulative “wear-out” risks for renal, hepatic, and hematologic events, whereas hypersensitivity and many pulmonary events followed random-failure patterns. Conclusions: This large-scale JADER analysis delineated the distinct safety profiles of the six anti-MRSA agents. The key findings included DAP pulmonary and muscle toxicities, LZD hematological events, and VCM nephrotoxicity. Time-to-onset modeling indicates potential cumulative versus random risk patterns, suggesting the need for individualized monitoring and cross-validation. Full article